Richie Bridgestone (whose parents are divorced) goes to spend the weekend with his father at his secluded mountain cabin. During a moonlight hike, they are attacked in the darkness by a creature that he recognizes as a werewolf . During the struggle, the werewolf falls into a ravine and is impaled by a wooden fence, but not before biting his father. Upon investigation, they find their attacker to be human and the sheriff concludes their attacker was an insane drifter. He spends the rest of the film trying to convince his mother, and his therapist that his father is now a werewolf.

PG | 1h 33min | Horror | 1 August 1973 (New York City, New York)
Possible in this day and age? Those who didn't believe... are dead! via Rob W

Synopsis:

Richie Bridgestone (whose parents are divorced) goes to spend the weekend with his father at his secluded mountain cabin. During a moonlight hike, they are attacked in the darkness by a creature that he recognizes as a werewolf. During the struggle, the werewolf falls into a ravine and is impaled by a wooden fence, but not before biting his father. Upon investigation, they find their attacker to be human and the sheriff concludes their attacker was an insane drifter. He spends the rest of the film trying to convince his mother, and his therapist that his father is now a werewolf.